Spongialization is an extension of the concept of Pridie for resurfacing damaged joints. The diseased cartilage is excised and the subchondral plate completely removed exposing the cancellous bone or "spongiosa" from which a new fibrous tissue surface can grow. The technique is particularly applicable to a localized lesion of the patella. Eighty-five patients who had patellar spongialization and were followed from 6--36 months (average 15 months) are reported, with 79% reporting good or excellent results. Provided that there was severe cartilage damage in each case, the early results are better than with either patellectomy or "shaving" of the diseased cartilage.